[Codewars] Snail (4 kyu) / JavaScript

https://www.codewars.com/kata/521c2db8ddc89b9b7a0000c1

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DESCRIPTION:

Snail Sort

Given an n x n array, return the array elements arranged from outermost elements to the middle element, traveling clockwise.

array = [[1,2,3],
         [4,5,6],
         [7,8,9]]
snail(array) #=> [1,2,3,6,9,8,7,4,5]

For better understanding, please follow the numbers of the next array consecutively:

array = [[1,2,3],
         [8,9,4],
         [7,6,5]]
snail(array) #=> [1,2,3,4,5,6,7,8,9]

This image will illustrate things more clearly:

NOTE: The idea is not sort the elements from the lowest value to the highest; the idea is to traverse the 2-d array in a clockwise snailshell pattern.

NOTE 2: The 0x0 (empty matrix) is represented as en empty array inside an array [[]].

 

코드

snail = function(array) {
  let rowStart = 0;
  let rowEnd = array.length - 1;
  let colStart = 0;
  let colEnd = array.length - 1;
  let result = [];

  
  while(true){
    for(let i = colStart; i <= colEnd; i++){
      if(array[rowStart][i]){
        result.push(array[rowStart][i]);
      }
    }
    rowStart++;
    
    for(let i = rowStart; i <= rowEnd; i++){
      if(array[i][colEnd]){
        result.push(array[i][colEnd]);
      }
    }
    colEnd--;
    
    for(let i = colEnd; i >= colStart; i--){
      if(array[rowEnd][i]){
        result.push(array[rowEnd][i]);
      }
    }
    rowEnd--;
    
    for(let i = rowEnd; i >= rowStart; i--){
      if(array[i][colStart]){
        result.push(array[i][colStart]);
      }
    }
    colStart++;
    
    if(rowStart > rowEnd && colStart > colEnd){
      break;
    }
  }
  return result;
}